Method of mass producing alternator stators for small engines

ABSTRACT

A plurality of stator core rings are produced, each having circumferentially spaced pole teeth arranged symmetrically to a diametral plane. Certain of the rings are wound with two like sets of windings of wire of one gage, each set confined to its own side of said plane. The remaining rings are similarly wound, but with wire of a different gage. Every ring is then severed on its said diametral plane, thus forming stator elements of two kinds that can be assembled to engines singly or in pairs, as needed.

This invention relates to the mass production of alternators intendedfor installation on small gasoline engines, and the invention is moreparticularly concerned with the volume production of alternator stators,each intended to be fixed to the crankcase portion of a small engine forcooperation with a permanent magnet carried by its flywheel.

Machines such as garden tractors and riding lawn mowers that are poweredby small gasoline engines are, to an increasing extent, equipped withauxiliary electrical systems for energizing such accessories asheadlights, engine starters and electric clutches. Since compactness,low cost and extreme sturdiness and durability are essentials of suchequipment, the primal current source for the electrical apparatus isusually an alternator driven by the engine.

In one arrangement that has proven to be both successful and popular,the alternator comprises an annular core, formed of a stack of identicallaminations and having circumferentially spaced pole teeth around whichcoils of wire are wound. The stator is fixed to the crankcase portion ofthe engine, in proximity to the flywheel and coaxial with it, so that apermanent magnet which is carried by the flywheel for orbital motion canpass in flux-linking relation to the pole teeth of the stator to inducealternating current in the windings.

With this arrangement the stator has two separate sets of windings, onefor an a.c. load circuit, the other for battery charging. The set ofwindings for the a.c. load circuit is of relatively heavy wire and isconnectable directly with lights and the like for energizing them withunrectified a.c. The other set of windings is connected with a storagebattery through a half-wave rectifier and is so designed that thecurrent through it is limited to a small enough value to insure againstovercharging of the battery, thereby making a regulator unnecessary.

In the alternator stator just described, the two sets of windings are atdiametrically opposite sides of the stator, and they have been wound onthe core simultaneously by means of a more or less conventional machinehaving two winding flyers. Although there was no particular problem inoperating the winding machine with wires of two different gages, nor inmaking it wind different numbers of turns on the respective sets ofcoils, there was some inefficiency in its operation inasmuch as itsflyer that wound the coils having the lesser number of turns had to beidle while the other flyer finished winding the other set of coils.

A more serious and costly inefficiency resulted from the desire tosatisfy all customer preferences. Some customers desire engines equippedwith stators on which only the heavier gage coils are wound, to be usedfor machines that are equipped with lights but have no battery. Otherswant their engines to have stators with only the lighter gage windings,for powering machines that have batteries but no a.c. loads. Stillothers want stators that are wound with both types of windings, formachines having both a battery and an a.c. load circuit. To satisfy allof these desires it was necessary to manufacture and stock all threetypes of stators. Furthermore, those customers who wanted only one typeof winding on their stators received a certain amount of core metal thatthey did not actually need.

By contrast, the present invention has as its general object to providea method of mass producing alternator stators of the character describedwhereby increased efficiency and economy is achieved in several respectsas compared with the prior practice, and, which, in particular, improvesthe efficiency of winding machine operation, reduces from three to twothe number of different types of stators that must be stocked to meetall customer requirements, materially reduces the bulk of stators notyet installed on engines, and eliminates the inclusion of unnecessarycore metal in stators having only one set of windings.

It is a more specific object of this invention to reduce the cost ofrepairing an alternator of the character described, in the event anultimate consumer finds that stator replacement is necessary.

It is also a specific object of this invention to reduce the cost ofmanufacturing, stocking and handling alternator stators having two setsof windings, one for a.c. load energization and one for unregulatedbattery charging.

Another object of this invention is to provide an inexpensive method ofmass producing very versatile stator elements which are capable of beinginstalled on engines either singly or in any of a number of differentcombinations and which are thus capable of meeting economically a largevariety of customer requirements.

With these observations and objectives in mind, the manner in which theinvention achieves its purpose will be appreciated from the followingdescription and the accompanying drawings, which exemplify theinvention, it being understood that changes may be made in the precisemethod of practicing the invention that is disclosed herein withoutdeparting from the essentials of the invention set forth in the appendedclaims.

The accompanying drawings illustrate one complete example of anembodiment of the invention practiced according to the best mode so fardevised for the practical application of the principles thereof, and inwhich:

FIG. 1 is a plan view of an alternator stator made in accordance withthe method of this invention, intended for use in an electrical systemhaving both an a.c. load circuit and an unregulated battery chargingcircuit, said circuits being illustrated diagrammatically; and

FIG. 2 is a somewhat pictorialized block diagram of the steps in themass production method of this invention, with simplified depictions ofthose structures that are illustrated.

Referring now to the accompanying drawings, the numeral 5 designatesgenerally an alternator stator which has been manufactured in accordancewith the principles of this invention and which comprises, in general,an annular core 6 having radially outwardly projecting pole teeth 7 atsubstantially uniform intervals around its periphery, and two sets ofwindings, respectively designated 8 and 9, which are wound around thepole teeth. The stator 5 is intended to be mounted on the body of asmall engine, adjacent to its flywheel and coaxial therewith, so that asthe fly wheel rotates a permanent magnet that is carried by it chargesinto the pole teeth 7 a varying flux that induces an alternating currentin each of the winding sets 8 and 9. For simplicity, the engine, itsflywheel and the magnet are not illustrated, these being well known.

It will be understood that the core 6 is made up of stacked identicallaminations, as is conventional, but in this case the core has a novelfeature in that it is made in two halves, divided from one another alonga diametral line indicated at 10; but these two halves are so juxtaposedas to be the functional equivalent of an integral annular core. Each ofthe sets of windings 8 and 9 is wound around the pole teeth 7 of onecore half.

The winding set 8 is wound of a heavier gage wire than the set 9 and hasa lesser number of turns. Thus the a.c. induced in the winding set 8 issuitable to be applied directly to the energization of headlights 12. Aswitch 13 in the circuit comprising the winding set 8 and headlights 12enables the lights to be turned on and off.

The winding set 9 is connected in series with a storage battery 14 and adiode 15 that provides for halfwave rectification. It will be understoodthat the parameters of winding 8 are such that there is no tendency forthe battery to be overcharged even though there is no regulator in thecircuit. To enable the headlights to be energized from the battery attimes when the engine is not running, the switch 13 can be adouble-throw switch with a central "off" position, as shown, and canhave one of its stationary contacts connected with the battery by meansof a conductor 16.

The stator core 6 as a whole is symmetrical to the line of division 10,so that the two core halves are identical to one another, and each ofthe winding sets 8 and 9 is confined to its own half of the core.Therefore if the stator is to be installed in a system that providesonly a.c. light energization, the core half comprising the winding set 9can be omitted; and, similarly, for an electrical system that providesonly for battery charging, only the core half having the winding set 9need be used. Note that two of the pole teeth of each core half,designated by 7', located symmetrically with respect to the core half,have no windings around them but instead have holes 18 through them toreceive bolts (not shown) or the like by which the core half can besecured to an engine body.

The method of mass producing stators according to the principles of thisinvention starts with the production of a plurality of annular statorcore rings 6' which can be identical with the laminated stator 6illustrated in FIG. 1 except that they are not divided into halves butare complete, integral annuli.

On certain of these stator core rings 106 two sets of the windings 8 arewound. Note that the two windings 8 on each of such rings are to beidentical to one another, and that each of such windings sets will beconfined to one side of the plane of symmetry of the ring that isdefined by the line 10 in FIG. 1. Because these two windings areidentical, they can be efficiently wound simultaneously on a two-flyerwinding machine that has its flyers moving in unison, without the needfor either flyer to be idle while the other completes its winding cycle.

In like manner each of the remaining core rings 206 has wound on it twoof the winding sets of the other type, corresponding to the winding 9 inFIG. 1. Again, each of these winding sets 9 is confined to its own halfof the core ring so that the wound ring is symmetrical to a planecorresponding to the line 10 in FIG. 1.

When the windings are finished, all of the core rings 106 and 206 arecut in half on the diametral plane through each that corresponds to theline 10 in FIG. 1. Such severing can be effected in any expeditiousmanner, as by shearing or sawing. The conventional coating of thewindings with epoxy or the like is preferably accomplished before thesevering operation, but it can be performed afterward.

The severing of the several core rings produces a supply of statorelements 105 and 205 of two kinds, one kind (denoted by 105) havingwindings of the type corresponding to the winding 8 in FIG. 1, the other(denoted by 205) having windings like the winding 9. Such statorelements can be assembled to engines as necessary to meet customerdesires, in any of several different arrangements.

Thus, for a customer who builds engine powered machines with bothheadlight and battery circuits, one of each of the stator elements 105and 205 will be installed on each engine 120, to provide an annularstator like that illustrated in FIG. 1. Only a stator element 105 willbe installed on each engine 220 for a customer who desires only anunrectified a.c. power source, and only a stator 205 will be installedon each engine 320 for a customer who wants only a source of batterycharging current.

However, the manufacture of the stator elements 105 and 205 makes itpossible to satisfy other customer requirements that could notheretofore be met economically. For example, if a customer requires nobattery charging capability but wants rather powerful headlightenergization, as on an engine intended for a snowmobile, each engine 420for that customer can be equipped with two of the stator elements 105,both of them connectable with the headlight circuit, either in series orin parallel in accordance with the type of lights to be used. In likemanner, if a customer wishes to have heavy duty battery chargingcapability but has no need for an unrectified a.c. source, each engine520 for such customer can be equipped with two of the stator elements205.

Note that the half-annular stator elements 105 and 205 are much morecompact than complete annuli of corresponding dimensions and cantherefore be stored, packaged and shipped at much less cost than theprior full ring stators that they supersede. It is also noteworthy thata customer who requires only one type of electrical output obtains itwith a stator that has no unnecessary core metal.

One final advantage of the invention is worth mentioning because itinures directly to the ultimate consumer, even though he may never haveoccasion to experience it. Alternator stators seldom fail or becomedamaged in service; but when this does happen with a stator having twowindings, it is almost invariably only one of the windings that becomesdefective. With stators manufactured in accordance with the principlesof the present invention, the consumer need only purchase a statorelement to replace the one having the defective winding, instead ofbeing compelled, as formerly, to purchase at substantially greaterexpense an entire core ring and two windings.

From the foregoing description taken with the accompanying drawings itwill be apparent that this invention provides a method of mass producingalternator stators for small gasoline engines whereby substantiallyconventional stators of various types can be manufactured efficientlyand in a manner that achieves economy not only in manufacturing but alsoin storage, shipping, inventory and repair.

Those skilled in the art will appreciate that the invention can beembodied in forms other than as herein disclosed for purposes ofillustration.

The invention is defined by the following claims:
 1. The method of massproducing alternator stators intended to be installed on small enginesfor cooperation with permanent magnets carried by their flywheels, toenable certain of such engines to be equipped with a type of alternatingcurrent source suitable for powering load circuits such as headlights,others to be equipped with a type of alternating current sourcesuitable, when rectified, for unregulated battery charging, and stillothers to be equipped with both types of alternating current sources,said method being characterized by:A. manufacturing a plurality ofidentical substantially annular stator core rings, each having an evennumber of circumferentially spaced pole teeth and being symmetrical to adiametral line; B. winding on the pole teeth of each of a certain numberof said rings two sets of windings of wire of one gage, said sets ofwindings being at opposite sides of said diametral line, each beingwholly at its side of said line, and the two sets being identical to oneanother; C. similarly winding on each of the remainder of said rings twoidentical sets of windings of wire of another gage; and D. cutting allof said stator rings in half on said diametral line.
 2. The method ofmass producing alternator stators for small engines for cooperation withpermanent magnets carried by their flywheels and each of which statorscomprises an annular core having a plurality of circumferentially spacedpole teeth, a set of windings of a first type, wound around pole teethat one side of the core and adapted to have induced in it a currentsuitable for energizing an a.c. load such as a light circuit, and a setof windings of a second type, wound around pole teeth at thediametrically opposite side of the core and adapted to have induced init a current which, when rectified, is suitable for unregulated batterycharging, said method being characterized by:A. winding on each of afirst plurality of annular core rings two sets of windings of said firsttype, at diametrically opposite sides of the ring, each set of windingsbeing confined to its own side of the ring; B. similarly winding on eachof a second plurality of annular core rings two sets of windings of saidsecond type; C. cutting all of said annular core rings in half, each ona diametral line lying between the sets of windings thereon, so thateach half of a core ring contains a complete set of windings; and D.assembling to each engine one wound ring half of said first pluralityand one wound ring half of said second plurality. .Iadd.
 3. The methodof mass producing alternator stators intended to be installed on smallengines for cooperation with permanent magnets carried by theirflywheels, to enable certain of such engines to be equipped with a typeof alternating current source suitable for powering load circuits suchas headlights, others to be equipped with a type of alternating currentsource suitable, when rectified, for unregulated battery charging, andstill others to be equipped with both types of alternating currentsources, said method being characterized by: A. producing a plurality ofidentical substantially annular stator core rings, each having an evennumber of circumferentially spaced pole teeth and being symmetrical to adiametral line so as to be separable on said line to provide a pair ofidentical half rings; B. winding on the pole teeth of each of a certainnumber of said rings two identical sets of windings of wire of one gage,said sets of windings being at opposite sides of said diametral line andeach being wholly at its side of said line so that the half rings intowhich each of said certain rings can be separated on said line aridentically wound; C. similarly winding on each of the remainder of saidrings two identical sets of windings of wire of another gage; and D.after winding, separating all of said rings, each on its said diametralline, into wound half rings. .Iaddend. .Iadd.
 4. The method of massproducing alternator stators for small engines for cooperation withpermanent magnets carried by their flywheels and each of which statorscomprises an annular core having a plurality of circumferentially spacedpole teeth, a set of windings of a first type, wound around pole teethat one side of the core and adapted to have induced in it a currentsuitable for energizing an a.c. load such as a light circuit, and a setof windings of a second type, wound around pole teeth at thediametrically opposite side of the core and adapted to have induced init a current which, when rectified, is suitable for unregulated batterycharging, said method being characterized by: A. winding on each of afirst plurality of annular core rings two sets of windings of said firsttype, at diametrically opposite sides of the ring, each set of windingsbeing confined to its own side of the ring so that each of said firstplurality of rings is separable on a diametral line lying between thetwo sets of windings thereon into two identical wound half rings; B.similarly winding on a second plurality of annular core rings two setsof windings of said second type; C. separating all of said wound corerings, each on its said diametral line, into wound half rings, each ofwhich comprises a complete set of windings; and D. assembling to eachengine one wound half ring of said first plurality and one wound halfring of said second plurality. .Iaddend.